Hydro-mechanical-damage model for the secondary creep of fiber reinforced mortar at high stress-to-strength ratio

Abstract

Recent works have showed that the secondary creep of concrete under sustained high load level of load-to-strength ratio is likely due to a strong coupling between damage and drying shrinkage, which locally occurs in the fracture process zone. The scope of this work is to develop a simplified damage-poromechanical model for the secondary creep of concrete, which directly accounts for such coupling. It was simply assumed that microcracking affects the distribution of the moisture content by scaling the adsorption isotherm with damage. The proposed hydro-mechanical-damage model couplings has been implemented into a discrete lattice method based on dually coupled conduit elements and mechanical element. Notably, the drying shrinkage is accounted within the poromechanical framework of the partially saturated media. The hydro-mechanical-damage model can engender microcrack process zone which govers the secondary creep of concrete at high stress. The model has been validated on 2D experiments of secondary creep on FRC which considers the effect of water-to-cement ratio and aggregate inclusion Finally, the model is validated against experimental results on secondary creep fiber reinforced mortar (FRM) beam considering the effect of concrete heterogeneity.